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Fix in MPI psum example....
Brian Granger -
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@@ -85,7 +85,7 b' Actually using MPI'
85 Once the engines are running with MPI enabled, you are ready to go. You can
85 Once the engines are running with MPI enabled, you are ready to go. You can
86 now call any code that uses MPI in the IPython engines. And, all of this can
86 now call any code that uses MPI in the IPython engines. And, all of this can
87 be done interactively. Here we show a simple example that uses mpi4py
87 be done interactively. Here we show a simple example that uses mpi4py
88 [mpi4py]_.
88 [mpi4py]_ version 1.1.0 or later.
89
89
90 First, lets define a simply function that uses MPI to calculate the sum of a
90 First, lets define a simply function that uses MPI to calculate the sum of a
91 distributed array. Save the following text in a file called :file:`psum.py`:
91 distributed array. Save the following text in a file called :file:`psum.py`:
@@ -94,10 +94,14 b' distributed array. Save the following text in a file called :file:`psum.py`:'
94
94
95 from mpi4py import MPI
95 from mpi4py import MPI
96 import numpy as np
96 import numpy as np
97
97
98 def psum(a):
98 def psum(a):
99 s = np.sum(a)
99 s = np.sum(a)
100 return MPI.COMM_WORLD.Allreduce(s,MPI.SUM)
100 rcvBuf = np.array(0.0,'d')
101 MPI.COMM_WORLD.Allreduce([s, MPI.DOUBLE],
102 [rcvBuf, MPI.DOUBLE],
103 op=MPI.SUM)
104 return rcvBuf
101
105
102 Now, start an IPython cluster in the same directory as :file:`psum.py`::
106 Now, start an IPython cluster in the same directory as :file:`psum.py`::
103
107
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